An effective Solid Electrolyte Interface layer (SEI) must be created at the surface of a graphite negative electrode of a battery in order to keep the electrolyte from decomposing. Various electrolytes comprising certain combinations of salts and solvents produce SEI layers of various qualities. Typical lithium ion batteries use an electrolyte comprising LiPF6 in a carbonate solvent, with 1.2-M LiPF6 in ethylene carbonate (EC): diethyl carbonate (DEC) being typical in the battery industry. EC is solid at room temperature and requires additional processing steps for employing in an electrolyte. Graphite electrodes have a fragile structure and, until the invention of the electrolyte described herein, have required the use of EC for forming the SEI layer without damaging the graphite structure. By contrast, hard carbon negative electrodes are not as easily broken and therefore can use solvents other than EC to form the SEI layer. However, while hard carbon has a higher capacity than graphite, it can absorb a lot of moisture and has a large irreversible capacity, making graphite a much more desirable electrode material than hard carbon. Vinylene carbonate (VC) and vinyl ethylene carbonate (VEC) can aid in creating an SEI layer, but is preferably used in small quantities because an excess of these solvents creates degradation at the positive electrode; with this small quantity of SEI-forming solvent, only a thin SEI layer is created, with all of the VC or VEC consumed during the first charging cycle; therefore, another SEI-forming component such as EC must be added.